生物诱抗剂草酸对黄瓜叶片中过氧化物酶的系统诱导作用

 本文进一步证明草酸是一种有效的非生物诱抗剂,它能显著提高黄瓜对炭疽病的系统抗性,进而研究了草酸对黄瓜叶片中与抗病有关的过氧化物酶(POD)的系统诱导作用及其内在机理。结果表明:40mmol/L草酸诱导可溶态POD活性效果最佳;在测定时间范围内,草酸诱导的可溶态POD活性在第7d后逐渐下降,而细胞壁离子键结合态POD活性被诱导后保持稳定;草酸在快带区诱导出一种新的POD同功酶,其Rf值为0.63;自由基清除剂甘露醇和抗坏血酸可明显抑制草酸对可溶态POD活性的诱导作用;草酸诱导可溶态POD的作用信号可在5h左右从被处理的第1片真叶传导至未处理的第2片真叶,被处理叶的保留时间越长,其诱导效果越好。

THE SYSTEMIC INDUCTION OF PEROXIDASE BY OXALATE IN CUCUMBER LEAVES

In this study,it was further confirmed that oxalate was able to induce the systemic resistance of cucumber to Colletotrichum orbiculare.The treatment with oxalate reduced necrosis number by 49.7% and necrosis area by 58.6% compared with control.Correspondingly the systemic induction of peroxidase(POD) by oxalate,which may be closely correlated with resistance to pathogen,was investigated in cucumber.The results are as follows:(1)The induction of souble POD activity was increased with the increase in the concentrations (10~40 mmol/L), reaching maximum at 40 mmol/L;(2) During 7 to 13 days after treatment with oxalate,the induced soulble POD activity started declining whereas the ionically cell wall-bound POD activity still remained at the induced level;(3) A new isozyme of POD was identified by native PAGE with thinlayer scanning in oxalate-treated cucumber leaves,in which the Rf is about 0.63;(4) The induction of souble POD could be inhibited by free radical scavengers manitol and ascorbate;(5) Signal transduction from the first true leaf to the second entailed about 5h for the systemic induction of POD after oxalate-treatment.The induction effectiveness was enhanced if the treated leaf remained longer on the plant.